Refactor partitionConsumer a bit
Refactor partitionConsumer a bit

Move all redispatch/error logic out of `handleResponse` and into a single if
statement, based on the new return value of `handleResponse`.

jimmykuo/sarama,kmiku7/sarama,pronix/sarama,rafrombrc/sarama,winlinvip/sarama,LastManStanding/sarama,jepst/sarama,raisemarketplace/sarama,mailgun/sarama,vrischmann/sarama,scalingdata/sarama,aybabtme/sarama,rafrombrc/sarama,HelixEducation/sarama,cep21/sarama,kraveio/sarama,DataDog/sarama,yangfan876/sarama,raisemarketplace/sarama,Neuw84/sarama,kraveio/sarama,LastManStanding/sarama,winlinvip/sarama,Shopify/sarama,VividCortex/sarama,pronix/sarama,DataDog/sarama,jepst/sarama,uovobw/sarama,remerge/sarama,VividCortex/sarama,aybabtme/sarama,HelixEducation/sarama,scalingdata/sarama,vrischmann/sarama,mailgun/sarama,remerge/sarama,Neuw84/sarama,crast/sarama,jimmykuo/sarama,yangfan876/sarama,cep21/sarama,crast/sarama,Shopify/sarama,kmiku7/sarama,uovobw/sarama